The present invention relates to a vent apparatus, and particularly to a vent apparatus for regulating discharge of liquid fuel and fuel vapor from a fuel tank.
Vehicle fuel systems include fuel tanks and various valves for venting pressurized fuel vapor from the tank to a fuel vapor recovery canister onboard the vehicle. Roll-over valves and fill-limit valves are examples of fuel system valves included in vehicle fuel systems.
Fuel vapor is generated in the fuel tank during operation of the vehicle, for example, by evaporation or by sloshing of the liquid fuel against the walls of the fuel tank. Excessive pressure can build up in the fuel tank unless fuel system valves are provided to vent fuel vapor from the fuel tank in certain circumstances. Each fuel system valve is movable between an opened position allowing fuel vapor to vent from the fuel tank through a tank vent outlet and a closed position blocking fuel vapor from venting from the fuel tank through the tank vent outlet.
According to the present disclosure, a vent apparatus is adapted for use with a fuel tank to control venting of fuel vapor from the fuel tank. The vent apparatus comprises a fuel vapor vent outlet to discharge fuel vapor from the fuel tank. The vent apparatus comprises a normally open first valve module to serve as a fuel fill limit valve and close when the liquid level in the tank reaches a predetermined fill limit and a normally open second valve module to serve as a fuel fill limit valve and close when the liquid level in the tank reaches the predetermined fill limit. The first valve module and the second valve module cooperate to block communication between the fuel tank and the fuel vapor vent outlet when the vent apparatus is positioned in a non-tilted orientation relative to a horizontal and the level of liquid fuel in the fuel tank reaches the predetermined fill limit to close both valve modules.
According to another aspect of the disclosure, the vent apparatus has a housing having the fuel vapor vent outlet to discharge fuel vapor from the fuel tank, a first lower fuel vapor vent aperture, and a second upper fuel vapor vent aperture. The first valve module is a lower roll-over valve module associated with the lower fuel vapor vent aperture. The second valve module is an upper roll-over valve module associated with the upper fuel vapor vent aperture. The lower roll-over valve module and the upper roll-over valve module are movable between a fill-limit orientation and a venting orientation. In the fill-limit orientation, the lower roll-over valve module and the upper roll-over valve module cooperate to block communication between the fuel tank and the fuel vapor vent outlet through the lower fuel vapor vent aperture and the upper fuel vapor vent aperture when the level of liquid fuel in the fuel tank rises to a predetermined fill limit. In the venting orientation, the lower roll-over valve module blocks communication between the fuel tank and the fuel vapor vent outlet through the lower fuel vapor vent aperture and the upper roll-over valve module allows fuel vapor to flow from the fuel tank through the upper fuel vapor vent aperture to the fuel vapor vent outlet.
According to another aspect of the disclosure, the housing further has a first chamber, a second chamber, a third chamber, and a liquid fuel transfer aperture for communication of liquid fuel between the first chamber and the third chamber. The first valve module is positioned for movement in the first chamber between an opened position allowing fuel vapor to flow from the first chamber through the first fuel vapor vent aperture to the second chamber for discharge through the fuel vapor vent outlet and a closed position blocking fuel from flowing from the first chamber through the first fuel vapor vent aperture to the second chamber. The second valve module is positioned for movement in the third chamber from an opened position allowing fuel vapor to flow from the third chamber through the second fuel vapor vent aperture to the second chamber for discharge through the fuel vapor vent outlet to a closed position blocking fuel from flowing from the third chamber through the second fuel vapor vent aperture to the second chamber in response to liquid fuel flowing from the first chamber through the liquid fuel transfer aperture to the third chamber.
Additional features of the disclosure will become apparent to those skilled in the art upon consideration of the following detailed description of illustrative embodiments exemplifying the best mode as presently perceived.